Organic electroluminescent device

ABSTRACT

An organic electroluminescent device includes: a pair of electrodes; and at least one organic compound layer therebetween, the at least one organic compound layer comprises at least a light-emitting layer, wherein at least one of the at least one organic compound layer comprises at least one compound represented by a particular formula.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 11/709,791 filed Feb. 23,2007, which claims benefit of Japanese Patent Application No.2006-047153 filed Feb. 23, 2006; the above noted prior applications areall hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic electro-luminescent deviceof emitting light by converting electric energy into light.

2. Description of the Related Art

An organic electroluminescent device is being aggressively studied anddeveloped because light emission of high brightness can be obtained bylow-voltage driving. The organic electroluminescent device has anorganic layer between a pair of electrodes, and this is a device wherean electron injected from a cathode and a hole injected from an anodeare recombined in the organic layer and the energy of an excitonproduced is utilized for light emission.

In recent years, the devices are becoming highly efficient by the use ofa phosphorescent material. There have been disclosed inventions relatedto a phosphorescent device using an iridium complex, a platinum complex(see, U.S. Pat. No. 6,303,238 and International Publication 00/57676,pamphlet) or the like as the phosphorescent material, but a devicesatisfying both high efficiency and high durability has not yet beendeveloped.

Also, inventions related to an organic EL device using a polyarylenematerial as a high-durability material have been disclosed (see, forexample, JP-A-2002-356449 (the term “JP-A” as used herein means an“unexamined published Japanese patent application”)). However, thematerials used therein have a condensed ring or a long conjugate systemand all are low in the lowest excited triplet level (T₁ level) ofmolecule and when used for a phosphorescent device, such a materialquenches the light emitted from the phosphorescent material to decreasethe light emission efficiency. This is prominent in the emission oflight at a short wavelength, and serious quenching of light emissionoccurs particularly on use for a blue phosphorescent device.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an organicelectroluminescent device assured of high light emission efficiency andhigh durability.

The present inventors have made studies so as to attain theabove-described object, as a result, it has been found that thoseproblems can be solved by an organic electroluminescent device where anaromatic compound having a specific structure is contained in theorganic compound layer. That is, the present invention has been achievedby the following means.

[1] An organic electroluminescent device, which comprises:

a pair of electrodes; and

at least one organic compound layer between the pair of electrodes, theat least one organic compound layer comprises at least a light-emittinglayer,

wherein at least one of the at least one organic compound layercomprises at least one compound represented by formula (1):

wherein Q¹ to Q⁴ each independently represents an atomic group forforming an aromatic hydrocarbon ring or an aromatic heterocyclic ring incombination with two carbon atoms in formula (1);

A¹ and A² each independently represents a carbon atom or a nitrogenatom; and

Q⁵ and Q⁶ each independently represents an atomic group for forming anaromatic hydrocarbon ring or an aromatic heterocyclic ring incombination with A¹ and A² respectively, provided that Q⁵ and Q⁶ are notcombined through a single bond, a divalent aromatic hydrocarbon ringgroup or a divalent aromatic heterocyclic ring group.

[2] The organic electroluminescent device as described in [1] above,

wherein the at least one compound represented by formula (1) has a glasstransition temperature of from 130 to 450° C.

[3] The organic electroluminescent device as described in [1] or [2]above,

wherein the at least one compound represented by formula (1) has thelowest excited triplet energy level of from 63 kcal/mol (263.97 kJ/mol)to 95 kcal/mol (398.05 kJ/mol).

[4] The organic electroluminescent device as described in any of [1] to[3] above, wherein the light-emitting layer comprises a light-emittingmaterial, and

wherein the light-emitting material comprises at least a phosphorescentmaterial.

[5] The organic electroluminescent device as described in [4] above,

wherein the phosphorescent material is an iridium complex or a platinumcomplex.

[6] The organic electroluminescent device as described in any of [1] to[5] above,

wherein the light-emitting layer comprises the at least one compoundrepresented by formula (1).

[7] The organic electroluminescent device as described in any of [1] to[6] above,

wherein the at least one compound represented by formula (1) isrepresented by formula (2):

wherein A¹ and A² each independently represents a carbon atom or anitrogen atom;

Q⁵ and Q⁶ each independently represents an atomic group for forming anaromatic hydrocarbon ring or an aromatic heterocyclic ring incombination with A¹ and A² respectively, provided that Q⁵ and Q⁶ are notcombined through a single bond, a divalent aromatic hydrocarbon ringgroup or a divalent aromatic heterocyclic ring group;

A^(n) (n=201 to 216) each independently represents N or C—R^(n) (n=201to 216); and

R²⁰¹ to R²¹⁶ each independently represents a hydrogen atom or asubstituent.

[8] The organic electroluminescent device as described in [7] above,

wherein the at least one compound represented by formula (2) isrepresented by formula (3):

wherein A¹ and A² each independently represents a carbon atom or anitrogen atom;

Q⁵ and Q⁶ each independently represents an atomic group for forming anaromatic hydrocarbon ring or an aromatic heterocyclic ring incombination with A¹ and A² respectively, provided that Q⁵ and Q⁶ are notcombined through a single bond, a divalent aromatic hydrocarbon ringgroup or a divalent aromatic heterocyclic ring group;

A^(n) (n=31 to 38) each independently represents N or C—R^(n) (n=31 to38);

R³¹ to R³⁸ each independently represents a hydrogen atom or asubstituent; and

R¹ to R⁸ each independently represents a hydrogen atom or a substituent.

[9] The organic electroluminescent device as described in [8] above,

wherein the at least one compound represented by formula (3) isrepresented by formula (4):

wherein Q⁴¹ and Q⁴² each independently represents an atomic group forforming an aromatic hydrocarbon ring or an aromatic heterocyclic ring incombination with the carbon atom in formula (4), provided that Q⁴¹ andQ⁴² are not combined through a single bond, a divalent aromatichydrocarbon ring group or a divalent aromatic heterocyclic ring group;

A^(n) (n=31 to 38) each independently represents N or C—R^(n) (n=31 to38);

R³¹ to R³⁸ each independently represents a hydrogen atom or asubstituent; and

R¹ to R⁸ each independently represents a hydrogen atom or a substituent.

[10] The organic electroluminescent device as described in [9] above,

wherein the at least one compound represented by formula (4) isrepresented by formula (5):

wherein A^(n) (n=31 to 38 and 501 to 510) each independently representsN or C—R^(n) (n=31 to 38 and 501 to 510);

R³¹ to R³⁸ and R⁵⁰¹ to R⁵¹⁰ each independently represents a hydrogenatom or a substituent; and

R¹ to R⁸ each independently represents a hydrogen atom or a substituent.

[11] The organic electroluminescent device as described in [4] above,

wherein the phosphorescent material is a platinum complex of atetradentate ligand.

[12] The organic electroluminescent device as described in [4] above,

wherein the phosphorescent material is an iridium complex having afluorine-substituted phenyl group in a ligand.

DETAILED DESCRIPTION OF THE INVENTION

The organic electroluminescent device of the present invention has atleast one organic light-emitting layer (light-emitting layer) as anorganic compound layer. As for the organic compound layer other than thelight-emitting layer, for example, a hole injection layer, a holetransport layer, an electron blocking layer, an exciton blocking layer,a hole blocking layer, an electron transport layer, an electroninjection layer and a protective layer may be appropriately disposed,and each layer may concurrently have a function of other layers. Also,each layer may be composed of a plurality of layers.

The organic electroluminescent device of the present invention mayutilize either light emission from an excited singlet state(fluorescence) or light emission from an excited triplet state(phosphorescence) but in view of emission efficiency, preferablyutilizes phosphorescence.

In the case where the organic electroluminescent device of the presentinvention utilizes phosphorescence, the light-emitting layer ispreferably composed of at least one kind of phosphorescent material andat least one kind of host material. Here, the host material is amaterial other than the light-emitting material among the materialsconstituting the light-emitting layer and means a material having atleast one function out of a function of holding the dispersedlight-emitting material in the layer, a function of receiving a holefrom an anode, a hole transport layer or the like, a function ofreceiving an electron from a cathode, an electron transport layer or thelike, a function of transporting a hole and/or an electron, a functionof providing a site for recombination of a hole and an electron, afunction of transferring the energy of an exciton produced by therecombination to the light-emitting material, and a function oftransporting a hole and/or an electron to the light-emitting material.

The compound of the present invention may be contained in any layer ofthe organic layers and may also be contained in a plurality of layersbut is preferably contained in the light-emitting layer, hole blockinglayer, electron transport layer or electron injection layer and mostpreferably contained as a host material in the light-emitting layer. Inthe case where the compound of the present invention is contained as ahost material in the light-emitting layer, the content thereof ispreferably from 50 to 99.9 mass %, more preferably from 60 to 99%. (Inthis specification, mass ratio is equal to weight ratio.) In the casewhere the compound of the present invention is contained in the holeblocking layer, electron transport layer and electron injection layer,the content thereof in each layer is preferably from 70 to 100%, morepreferably from 85 to 100%, and most preferably 100%. Furthermore, inthe case where the compound of the present invention is contained in theelectron blocking layer, hole transport layer and hole injection layer,the content thereof in each layer is preferably from 70 to 100%, morepreferably from 85 to 100%, and most preferably 100%.

The compound represented by formula (1) of the present invention isdescribed in detail below.

(wherein Q¹ to Q⁴ each independently represents an atomic group forforming an aromatic hydrocarbon ring or aromatic heterocyclic ring incombination with two carbon atoms in the formula, A¹ and A² eachindependently represents a carbon atom or a nitrogen atom, Q⁵ and Q⁶each independently represents an atomic group for forming an aromatichydrocarbon ring or aromatic heterocyclic ring in combination with A¹and A² respectively, and Q⁵ and Q⁶ are not combined through a singlebond, a divalent aromatic hydrocarbon ring group or a divalent aromaticheterocyclic ring group).

Q¹ to Q⁴ each independently represents an atomic group for forming anaromatic hydrocarbon ring or aromatic heterocyclic ring in combinationwith two carbon atoms in the formula. The aromatic hydrocarbon ring oraromatic heterocyclic ring constituted by Q¹, Q², Q³ or Q⁴ is notparticularly limited but is preferably a 4- to 10-membered ring, morepreferably a 5- to 7-membered ring, still more preferably a 5- or6-membered ring, yet still more preferably a 6-membered ring. Theheteroatom contained in the aromatic heterocyclic ring constituted byQ¹, Q², Q³ or Q⁴ is not particularly limited but is preferably nitrogen,oxygen, sulfur, selenium, silicon, germanium or phosphorus, morepreferably nitrogen, oxygen or sulfur, still more preferably nitrogen oroxygen, yet still more preferably nitrogen. The number of heteroatomscontained in one aromatic heterocyclic ring constituted by Q¹, Q², Q³ orQ⁴ is not particularly limited but is preferably from 1 to 3.

Specific examples of the aromatic hydrocarbon ring or aromaticheterocyclic ring constituted by Q¹, Q², Q³ or Q⁴ include a benzenering, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazinering, a triazine ring, a pyrrole ring, a pyrazole ring, an imidazolering, a triazole ring, an oxazole ring, an oxadiazole ring, a thiazolering, a thiadiazole ring, a furan ring, a thiophene ring, a selenophenering, a silole ring, a germole ring and a phosphole ring. The aromatichydrocarbon ring or aromatic heterocyclic ring constituted by Q¹, Q², Q³or Q⁴ is preferably a benzene ring, a pyridine ring, a pyrazine ring, apyrimidine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, anoxazole ring, a thiazole ring, a furan ring or a thiophene ring, morepreferably a benzene ring, a pyridine ring, a pyrazine ring, apyrimidine ring, an imidazole ring or a thiophene ring, still morepreferably a benzene ring, a pyrimidine ring, a pyrazine ring or apyrimidine ring, yet still more preferably a benzene ring, a pyridinering or a pyrazine ring.

The aromatic hydrocarbon ring or aromatic heterocyclic ring constitutedby Q¹, Q², Q³ or Q⁴ may have a substituent, and those in the followingsubstituent group A may be applied as the substituent.

(Substituent Group A)

An alkyl group (preferably having a carbon number of to 30, morepreferably from 1 to 20, still more preferably from 1 to 10, e.g.,methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl,cyclopropyl, cyclopentyl, cyclohexyl), an alkenyl group (preferablyhaving a carbon number of 2 to 30, more preferably from 2 to 20, stillmore preferably from 2 to 10, e.g., vinyl, allyl, 2-butenyl,3-pentenyl), an alkynyl group (preferably having a carbon number of 2 to30, more preferably from 2 to 20, still more preferably from 2 to 10,e.g., propargyl, 3-pentynyl), an aryl group (preferably having a carbonnumber of 6 to 30, more preferably from 6 to 20, still more preferablyfrom 6 to 12, e.g., phenyl, p-methylphenyl, naphthyl, anthranyl), anamino group (preferably having a carbon number of 0 to 30, morepreferably from 0 to 20, still more preferably from 0 to 10, e.g.,amino, methylamino, dimethylamino, diethylamino, dibenzylamino,diphenylamino, ditolylamino), an alkoxy group (preferably having acarbon number of 1 to 30, more preferably from 1 to 20, still morepreferably from 1 to 10, e.g., methoxy, ethoxy, butoxy,2-ethylhexyloxy), an aryloxy group (preferably having a carbon number of6 to 30, more preferably from 6 to 20, still more preferably from 6 to12, e.g., phenyloxy, 1-naphthyloxy, 2-naphthyloxy), a heterocyclic oxygroup (preferably having a carbon number of 1 to 30, more preferablyfrom 1 to 20, still more preferably from 1 to 12, e.g., pyridyloxy,pyrazyloxy, pyrimidyloxy, qunolyloxy), an acyl group (preferably havinga carbon number of 1 to 30, more preferably from 1 to 20, still morepreferably from 1 to 12, e.g., acetyl, benzoyl, formyl, pivaloyl), analkoxycarbonyl group (preferably having a carbon number of 2 to 30, morepreferably from 2 to 20, still more preferably from 2 to 12, e.g.,methoxycarbonyl, ethoxycarbonyl), an aryloxycarbonyl group (preferablyhaving a carbon number of 7 to 30, more preferably from 7 to 20, stillmore preferably from 7 to 12, e.g., phenyloxycarbonyl), an acyloxy group(preferably having a carbon number of 2 to 30, more preferably from 2 to20, still more preferably from 2 to 10, e.g., acetoxy, benzoyloxy), anacylamino group (preferably having a carbon number of 2 to 30, morepreferably from 2 to 20, still more preferably from 2 to 10, e.g.,acetylamino, benzoylamino), an alkoxycarbonylamino group (preferablyhaving a carbon number of 2 to 30, more preferably from 2 to 20, stillmore preferably from 2 to 12, e.g., methoxycarbonylamino), anaryloxycarbonylamino group (preferably having a carbon number of 7 to30, more preferably from 7 to 20, still more preferably from 7 to 12,e.g., phenyloxycarbonylamino), a sulfonylamino group (preferably havinga carbon number of 1 to 30, more preferably from 1 to 20, still morepreferably from 1 to 12, e.g., methanesulfonylamino,benzenesulfonyl-amino), a sulfamoyl group (preferably having a carbonnumber of 0 to 30, more preferably from 0 to 20, still more preferablyfrom 0 to 12, e.g., sulfamoyl, methylsulfamoyl, dimethylsulfamoyl,phenylsulfamoyl), a carbamoyl group (preferably having a carbon numberof 1 to 30, more preferably from 1 to 20, still more preferably from 1to 12, e.g., carbamoyl, methylcarbamoyl, diethylcarbamoyl,phenylcarbamoyl), an alkylthio group (preferably having a carbon numberof 1 to 30, more preferably from 1 to 20, still more preferably from 1to 12, e.g., methylthio, ethylthio), an arylthio group (preferablyhaving a carbon number of 6 to 30, more preferably from 6 to 20, stillmore preferably from 6 to 12, e.g., phenylthio), a heterocyclic thiogroup (preferably having a carbon number of 1 to 30, more preferablyfrom 1 to 20, still more preferably from 1 to 12, e.g., pyridylthio,2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzothiazolylthio), asulfonyl group (preferably having a carbon number of 1 to 30, morepreferably from 1 to 20, still more preferably from 1 to 12, e.g.,mesyl, tosyl), a sulfinyl group (preferably having a carbon number of 1to 30, more preferably from 1 to 20, still more preferably from 1 to 12,e.g., methanesulfinyl, benzenesulfinyl), a ureido group (preferablyhaving a carbon number of 1 to 30, more preferably from 1 to 20, stillmore preferably from 1 to 12, e.g., ureido, methylureido, phenylureido),a phosphoric acid amido group (preferably having a carbon number of 1 to30, more preferably from 1 to 20, still more preferably from 1 to 12,e.g., diethylphosphoric acid amido, phenylphosphoric acid amido), ahydroxyl group, a mercapto group, a halogen atom (e.g., fluorine,chlorine, bromine, iodine), a cyano group, a sulfo group, a carboxylgroup, a nitro group, a hydroxamic acid group, a sulfino group, ahydrazino group, an imino group, a heterocyclic group (preferably havinga carbon number of 1 to 30, more preferably from 1 to 12, with theheteroatom being, for example, nitrogen atom, oxygen atom or sulfuratom; e.g., imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl,morpholino, benz-oxazolyl, benzimidazolyl, benzothiazolyl, carbazolyl,azepinyl), a silyl group (preferably having a carbon number of 3 to 40,more preferably from 3 to 30, still more preferably from 3 to 24, e.g.,trimethylsilyl, triphenylsilyl), and a silyloxy group (preferably havinga carbon number of 3 to 40, more preferably from 3 to 30, still morepreferably from 3 to 24, e.g., trimethylsilyloxy, triphenylsilyloxy).

The substituent of the aromatic hydrocarbon ring or aromaticheterocyclic ring constituted by Q¹, Q², Q³ or Q⁴ is preferably an alkylgroup, an aryl group, an amino group, an alkoxy group, an aryloxy group,a heterocyclic oxy group, an acyl group, an alkylthio group, an arylthiogroup, a heterocyclic thio group, a sulfonyl group, a halogen atom, acyano group, a heterocyclic group or a silyl group, more preferably analkyl group, an aryl group, an alkoxy group, a halogen atom, a cyanogroup, a heterocyclic group or a silyl group, still more preferably analkyl group, an aryl group, a cyano group, a heterocyclic group or asilyl group, yet still more preferably an alkyl group, an aryl group, acyano group or a heterocyclic group.

The aromatic hydrocarbon ring or aromatic heterocyclic ring constitutedby Q¹, Q², Q³ or Q⁴ may form a condensed ring with another ring.Examples of the ring condensed with include a benzene ring, a pyridinering, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a pyrrolering, a pyrazole ring, an imidazole ring, a triazole ring, an oxazolering, an oxadiazole ring, a thiazole ring, a thiadiazole ring, a furanring, a thiophene ring, a selenophene ring, a silole ring, a germolering and a phosphole ring. The ring condensed with is preferably abenzene ring, a pyridine ring or a pyrazine ring. It is most preferredthat the aromatic hydrocarbon ring or aromatic heterocyclic ringconstituted by Q¹, Q², Q³ or Q⁴ does not form a condensed ring withanother ring.

The above-described substituents and condensed rings each may furtherhave a substituent or may be further condensed with another ring.

The aromatic hydrocarbon ring or aromatic heterocyclic ring constitutedby Q¹, Q², Q³ or Q⁴ is preferably a benzene ring, a pyridine ring, apyrazine ring, a pyrimidine ring, a triazine ring, a pyrrole ring, apyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, athiazole ring, a furan ring or a thiophene ring, more preferably abenzene ring, a pyridine ring, a pyrazine ring, a pyrrole ring, apyrazole ring, an imidazole ring, an oxazole ring, a thiazole ring or athiophene ring, still more preferably a benzene ring, a pyridine ring, apyrazine ring, a pyrazole ring, an imidazole ring or a thiophene ring,yet still more preferably a benzene ring, a pyridine ring or a pyrazinering.

A¹ and A² each independently represents a carbon atom or a nitrogenatom. Q⁵ and Q⁶ each independently represents an atomic group forforming an aromatic hydrocarbon ring or aromatic heterocyclic ring incombination with A¹ or A². Specific examples of the aromatic hydrocarbonring or aromatic heterocyclic ring formed by A¹ and Q⁵ and the aromatichydrocarbon ring or aromatic heterocyclic ring formed by A² and Q⁶include a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidinering, a pyridazine ring, a triazine ring, a pyrrole ring, a pyrazolering, an imidazole ring, a triazole ring, an oxazole ring, an oxadiazolering, a thiazole ring, a thiadiazole ring, a furan ring, a thiophenering, a selenophene ring, a silole ring, a germole ring and a phospholering. The aromatic hydrocarbon ring or aromatic heterocyclic ring formedby A¹ and Q⁵ and the aromatic hydrocarbon ring or aromatic heterocyclicring formed by A² and Q⁶ each is, when A¹ and A² are a carbon atom,preferably a benzene ring, a pyridine ring, a pyrazine ring, apyrimidine ring, a pyrrole ring, a pyrazole ring, an imidazole ring, anoxazole ring, a thiazole ring, a furan ring or a thiophene ring, morepreferably a benzene ring, a pyridine ring, a pyrazine ring, apyrimidine ring, an imidazole ring or a thiophene ring, still morepreferably a benzene ring, a pyrimidine ring, a pyrazine ring or animidazole ring, yet still more preferably a benzene ring, a pyridinering or a pyrazine ring, and when A¹ and A² are a nitrogen atom,preferably an imidazole ring, a pyrazole ring, a triazole ring or apyrrole ring, more preferably an imidazole ring, a pyrazole ring or atriazole ring, still more preferably an imidazole ring or a pyrazolering, yet still more preferably an imidazole ring.

Q⁵ and Q⁶ are not combined through a single bond or a divalent aromatichydrocarbon ring group or aromatic heterocyclic ring group. That is,formula (1) does not represent a cyclic hexaarylene compound. Also, thepairs of Q¹ and Q⁴, Q¹ and Q⁵, Q² and Q³, and Q² and Q⁶ each arepreferably not combined through a single bond.

The aromatic hydrocarbon ring or aromatic heterocyclic ring formed by A¹and Q⁵ and the aromatic hydrocarbon ring or aromatic heterocyclic ringformed by A² and Q⁶ each may have a substituent. As for the substituent,those described in the substituent group A above may be applied, and thepreferred range thereof is the same as the preferred range of thesubstituent possessed by the aromatic hydrocarbon ring or aromaticheterocyclic ring constituted by Q¹, Q², Q³ or Q⁴.

The aromatic hydrocarbon ring or aromatic heterocyclic ring formed by A¹and Q⁵ and the aromatic hydrocarbon ring or aromatic heterocyclic ringformed by A² and Q⁶ each may form a condensed ring with another ring. Asfor the ring condensed with, those described above as the ring condensedto the aromatic hydrocarbon ring or aromatic heterocyclic ringconstituted by Q¹, Q², Q³ or Q⁴ may be applied, and the preferred rangethereof is also the same. It is most preferred that the aromatichydrocarbon ring or aromatic heterocyclic ring formed by A¹ and Q⁵ andthe aromatic hydrocarbon ring or aromatic heterocyclic ring formed by A²and Q⁶ each does not form a condensed ring with another ring.

The compound represented by formula (1) is preferably a compoundrepresented by formula (2):

(wherein A¹ and A² each independently represents a carbon atom or anitrogen atom, Q⁵ and Q⁶ each independently represents an atomic groupfor forming an aromatic hydrocarbon ring or aromatic heterocyclic ringin combination with A¹ and A² respectively, Q⁵ and Q⁶ are not combinedthrough a single bond, a divalent aromatic hydrocarbon ring group or adivalent aromatic heterocyclic ring group, A^(n) (n=201 to 216) eachindependently represents N or C—R^(n) (n=201 to 216), and R²⁰¹ to R²¹⁶each independently represents a hydrogen atom or a substituent).

Formula (2) is described below.

In the formula, A¹, A², Q⁵ and Q⁶ have the same meanings as those informula (1), and preferred ranges are also the same. A^(n) (n=201 to216) each independently represents N or C—R^(n) (n=201 to 216), and R²⁰¹to R²¹⁶ each independently represents a hydrogen atom or a substituent.As for the substituent represented by R²⁰¹ to R²¹⁶, those described inthe substituent group A above may be applied. R²⁰¹ to R²¹⁶ each ispreferably a hydrogen atom, an alkyl group, an aryl group, an aminogroup, an alkoxy group, an aryloxy group, a heterocyclic oxy group, anacyl group, an alkylthio group, an arylthio group, a heterocyclic thiogroup, a sulfonyl group, a halogen atom, a cyano group, a heterocyclicgroup or a silyl group, more preferably a hydrogen atom, an alkyl group,an aryl group, an alkoxy group, a halogen atom, a cyano group, aheterocyclic group or a silyl group, still more preferably a hydrogenatom, an alkyl group, an aryl group, a cyano group, a heterocyclic groupor a silyl group, yet still more preferably a hydrogen atom, an alkylgroup, an aryl group, a cyano group or a heterocyclic group.

A²⁰¹ to A²⁰⁸ are preferably C—R²⁰¹ to C—R²⁰⁸. A²⁰⁹ to A²¹² arepreferably such that all are C—R^(n) (n=209 to 212) or one or two ofA²⁰⁹ to A²¹² is (are) N. Similarly, A²¹³ to A²¹⁶ are preferably suchthat all are C—R^(n) (n=213 to 216) or one or two of A²¹³ to A²¹⁶ is(are) N.

The compound represented by formula (2) is more preferably a compoundrepresented by formula (3):

(wherein A¹ and A² each independently represents a carbon atom or anitrogen atom, Q⁵ and Q⁶ each independently represents an atomic groupfor forming an aromatic hydrocarbon ring or aromatic heterocyclic ringin combination with A¹ and A² respectively, Q⁵ and Q⁶ are not combinedthrough a single bond, a divalent aromatic hydrocarbon ring group or adivalent aromatic heterocyclic ring group, A^(n) (n=31 to 38) eachindependently represents N or C—R^(n) (n=31 to 38), R³¹ to R³⁸ eachindependently represents a hydrogen atom or a substituent, and R¹ to R⁸each independently represents a hydrogen atom or a substituent).

The compound represented by formula (3) is described below.

In the formula, A¹, A², Q⁵ and Q⁶ have the same meanings as those informula (1), and preferred ranges are also the same. R¹ to R⁸ eachindependently represents a hydrogen atom or a substituent. As for thesubstituent represented by R¹ to R⁸, those described in the substituentgroup A above may be applied. R¹ to R⁸ each is preferably a hydrogenatom, an alkyl group, an aryl group, an amino group, an alkoxy group, anaryloxy group, a heterocyclic oxy group, an acyl group, an alkylthiogroup, an arylthio group, a heterocyclic thio group, a sulfonyl group, ahalogen atom, a cyano group, a heterocyclic group or a silyl group, morepreferably a hydrogen atom, an alkyl group, an aryl group, an alkoxygroup, a halogen atom, a cyano group, a heterocyclic group or a silylgroup, still more preferably a hydrogen atom, an alkyl group, an arylgroup, a cyano group, a heterocyclic group or a silyl group, yet stillmore preferably a hydrogen atom, an alkyl group, an aryl group, a cyanogroup or a heterocyclic group. A³¹ to A³⁴ have the same meanings as A²⁰⁹to A²¹² in formula (2), and preferred ranges are also the same.Similarly, A³⁵ to A³⁸ have the same meanings as A²¹³ to A²¹⁶ in formula(2), and preferred ranges are also the same.

The compound represented by formula (3) is more preferably a compoundrepresented by formula (4):

(wherein Q⁴¹ and Q⁴² each independently represents an atomic group forforming an aromatic hydrocarbon ring or aromatic heterocyclic ring incombination with the carbon atom, Q⁴¹ and Q⁴² are not combined through asingle bond, a divalent aromatic hydrocarbon ring group or a divalentaromatic heterocyclic ring group, A^(n) (n=31 to 38) each independentlyrepresents N or C—R^(n) (n=31 to 38), R³¹ to R³⁸ each independentlyrepresents a hydrogen atom or a substituent, and R¹ to R⁸ eachindependently represents a hydrogen atom or a substituent).

The compound represented by formula (4) is described below.

R¹ to R⁸ and A³¹ to A³⁸ have the same meanings as those in formula (3),and preferred ranges are also the same. Q⁴¹ and Q⁴² each independentlyrepresents an atomic group for forming an aromatic hydrocarbon ring oraromatic heterocyclic ring in combination with the carbon atom. Examplesof the aromatic hydrocarbon ring or aromatic heterocyclic ring by Q⁴¹ orQ⁴² include a benzene ring, a pyridine ring, a pyrazine ring, apyrimidine ring, a pyridazine ring, a triazine ring, a pyrrole ring, apyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, anoxadiazole ring, a thiazole ring, a thiadiazole ring, a furan ring, athiophene ring, a selenophene ring, a silole ring, a germole ring and aphosphole ring. The aromatic hydrocarbon ring or aromatic heterocyclicring formed by Q⁴¹ or Q⁴² is preferably a benzene ring, a pyridine ring,a pyrazine ring, a pyrimidine ring, a pyrrole ring, a pyrazole ring, animidazole ring, an oxazole ring, a thiazole ring, a furan ring or athiophene ring, more preferably a benzene ring, a pyridine ring, apyrazine ring, a pyrimidine ring, an imidazole ring or a thiophene ring,still more preferably a benzene ring, a pyrimidine ring, a pyrazine ringor an imidazole ring, yet still more preferably a benzene ring, apyridine ring or a pyrazine ring.

The compound represented by formula (4) is more preferably a compoundrepresented by formula (5):

(wherein A^(n) (n=31 to 38 and 501 to 510) each independently representsN or C—R^(n) (n=31 to 38 and 501 to 510), R³¹ to R³⁸ and R⁵⁰¹ to R⁵¹⁰each independently represents a hydrogen atom or a substituent, and R¹to R⁸ each independently represents a hydrogen atom or a substituent).

The compound represented by formula (5) is described below.

R¹ to R⁸ and A³¹ to A³⁸ have the same meanings as those in formula (3),and preferred ranges are also the same. A^(n) (n=501 to 510) eachindependently represents N or C—R^(n) (n=501 to 510), and R⁵⁰¹ to R⁵¹⁰each independently represents a hydrogen atom or a substituent. As forthe substituent represented by R⁵⁰¹ to R⁵¹⁰, those described in thesubstituent group A above may be applied. R⁵⁰¹ to R⁵¹⁰ each ispreferably a hydrogen atom, an alkyl group, an aryl group, an aminogroup, an alkoxy group, an aryloxy group, a heterocyclic oxy group, anacyl group, an alkylthio group, an arylthio group, a heterocyclic thiogroup, a sulfonyl group, a halogen atom, a cyano group, a heterocyclicgroup or a silyl group, more preferably a hydrogen atom, an alkyl group,an aryl group, an alkoxy group, a halogen atom, a cyano group, aheterocyclic group or a silyl group, still more preferably a hydrogenatom, an alkyl group, an aryl group, a cyano group, a heterocyclic groupor a silyl group, yet still more preferably a hydrogen atom, an alkylgroup, an aryl group, a cyano group or a heterocyclic group.

Specific examples of the compounds represented by formulae (1) to (5)are set forth below, but the present invention is not limited thereto.(Incidentally, Ph denotes a phenyl group, and ^(t)Bu denotes a tertiarybutyl group.)

The compounds of the present invention represented by formulae (1) to(5) can be synthesized by the methods described, for example, in Journalof the Chemical Society, Abstracts, 114-21 (January 1964) and Bulletinof the Chemical Society of Japan, 48(6), 1868-74 (1975) or by acombination of other known synthesis methods.

The synthesis method of the compound of the present invention isdescribed below by referring to specific examples.

Synthesis Example 1 Synthesis of Compound 1

In a nitrogen atmosphere, 1 g (3.21 mmol) of 2,2-dibromobiphenyl, 1.27 g(6.41 mmol) of 2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)biphenyl,168 mg (0.64 mmol) of triphenylphosphine, 2.39 g (17.3 mmol) ofpotassium carbonate, 36 mg (0.16 mmol) of palladium acetate, mL of1,2-dimethoxyethane and 30 mL of water were refluxed under heating for 2hours. The obtained reaction mixture was extracted with ethyl acetate,and the organic layer was washed with saturated brine and dried overanhydrous magnesium sulfate. After removing the solvent by distillationunder reduced pressure, recrystallization from an ethanol-chloroformmixed solvent was performed to obtain 0.70 g (yield: 48%) Compound 1 asa colorless cubic crystal.

Synthesis Example 2 Synthesis of Compound 165

In a nitrogen atmosphere, 1.5 g (3.96 mmol) of Compound A, 3.0 g (15.82mmol) of o-trifluoromethylphenyl-boric acid, 207 mg (0.79 mmol) oftriphenylphosphine, 2.95 g (21.4 mmol) of potassium carbonate, 44 mg(0.20 mmol) of palladium acetate, 15 mL of 1,2-dimethoxyethane and 20 mLof water were refluxed under heating for 5 hours. The obtained reactionmixture was extracted with ethyl acetate, and the organic layer waswashed with saturated brine and dried over anhydrous magnesium sulfate.After removing the solvent by distillation under reduced pressure,recrystallization from chloroform was performed to obtain 2.2 g (yield:92%) Compound 165 as a colorless powder crystal.

Considering the durability of the device, the glass transitiontemperature (Tg) of the compound of the present invention is preferablyfrom 130 to 450° C., more preferably from 135 to 450° C., still morepreferably from 140 to 450° C., yet still more preferably from 150 to450° C., and most preferably from 160 to 450° C.

Here, Tg can be confirmed, for example, by the thermal measurement suchas differential scanning calorimetry (DSC) and differential thermalanalysis (DTA) or by the X-ray diffraction (XRD) or polarizingmicroscope observation.

In the case where the light-emitting device of the present invention isa light-emitting device utilizing phosphorescence, the lowest excitedtriplet energy level (T₁ level) is preferably from 63 kcal/mol (263.97kJ/mol) to 95 kcal/mol (398.05 kJ/mol), more preferably from 67 kcal/mol(280.73 kJ/mol) to 95 kcal/mol (398.05 kJ/mol), still more preferablyfrom 69 kcal/mol (289.11 kJ/mol) to 95 kcal/mol (398.05 kJ/mol).

Here, the T₁ level can be obtained by measuring a phosphorescentspectrum of a material thin film and determining the level from theshort wavelength end.

The elements constituting the light-emitting device of the presentinvention are described in detail below.

<Substrate>

The substrate for use in the present invention is preferably a substratewhich does not scatter or attenuate the light emitted from the organiccompound layer. Specific examples thereof include an inorganic materialsuch as zirconia stabilized with yttrium (YSZ) and glass, and an organicmaterial such as polyester (e.g., polyethylene terephthalate,polybutylene phthalate, polyethylene naphthalate), polystyrene,polycarbonate, polyethersulfone, polyallylate, polyimide,polycycloolefin, norbornene resin and poly(chlorotrifluoroethylene).

For example, in the case of using glass as the substrate, theconstruction material used therefor is preferably non-alkali glass so asto reduce the ion dissolved out from the glass. Also, in the case ofusing soda lime glass, a barrier coat such as silica is preferablyapplied thereto before use. In the case of an organic material, thoseexcellent in the heat resistance, dimensional stability, solventresistance, electrical insulation and processability are preferred.

The shape, structure, size and the like of the substrate are notparticularly limited and may be appropriately selected, for example,according to the usage or purpose of the light-emitting device. Ingeneral, the substrate shape is preferably a plate form. The substratestructure may be a single-layer structure or a multilayer structure andmay be formed of a single member or two or more members.

The substrate may be colorless and transparent or may be colored andtransparent but from the standpoint that the light emitted from theorganic light-emitting layer is free from scattering, attenuation or thelike, the substrate is preferably colorless and transparent.

A moisture permeation-preventing layer (gas barrier layer) may beprovided on the front surface or back surface of the substrate.

As for the material of the moisture permeation-preventing layer (gasbarrier layer), an inorganic substance such as silicon nitride andsilicon oxide is suitably used. The moisture permeation-preventing layer(gas barrier layer) can be formed by, for example, a high-frequencysputtering method.

In the case of using a thermoplastic substrate, a hardcoat layer, anundercoat layer and the like may be further provided, if desired.

<Anode>

The anode is usually sufficient if it has a function as an electrode ofsupplying a hole to the organic compound layer. The shape, structure,size and the like thereof are not particularly limited, and the anodematerial may be appropriately selected from known electrode materialsaccording to the usage or purpose of the light-emitting device. Asdescribed above, the anode is usually provided as a transparent anode.

Suitable examples of the material for the anode include a metal, analloy, a metal oxide, an electrically conducting compound and a mixturethereof. Specific examples of the anode material include an electricallyconducting metal oxide such as tin oxide doped with antimony, fluorineor the like (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tinoxide (ITO) and indium zinc oxide (IZO); a metal such as gold, silver,chromium and nickel; a mixture or laminate of the metal and theelectrically conducting metal oxide; an inorganic electricallyconducting substance such as copper iodide and copper sulfide; anorganic electrically conducting material such as polyaniline,polythiophene and polypyrrole; and a laminate of such a material andITO. Among these, an electrically conducting metal oxide is preferred,and ITO is more preferred in view of productivity, high electricalconductivity, transparency and the like.

The anode can be formed on the substrate by a method appropriatelyselected, in consideration of suitability for the material constitutingthe anode, from a wet system such as printing and coating, a physicalsystem such as vacuum deposition, sputtering and ion plating, and achemical system such as CVD and plasma CVD. For example, in the case ofselecting ITO as the anode material, the anode may be formed by a DC orhigh-frequency sputtering method, a vacuum deposition method or an ionplating method.

In the organic electroluminescent device of the present invention, theposition where the anode is formed is not particularly limited and maybe appropriately selected according to the usage or purpose of thelight-emitting device, but the anode is preferably formed on thesubstrate. In this case, the anode may be formed entirely or partiallyon one surface of the substrate.

The patterning when forming the anode may be performed by chemicaletching such as photolithography, by physical etching using a laser orthe like, by vacuum deposition or sputtering using a mask, or by alift-off method or printing method.

The thickness of the anode may be appropriately selected according tothe material constituting the anode and cannot be indiscriminatelyspecified but is usually on the order of 10 nm to 50 preferably from 50nm to 20 μm.

The resistance value of the anode is preferably 10³ Ω/square or less,more preferably 10² Ω/square or less. In the case where the anode istransparent, the anode may be colorless and transparent or may becolored and transparent. In order to take out light from the transparentanode side, the transmittance of the anode is preferably 60% or more,more preferably 70% or more.

Incidentally, the transparent anode is described in detail in YutakaSawada (supervisor), Tomei Denkyoku Maku no Shin-Tenkai (New Developmentof Transparent Electrode Film, CMC (1999), and the matters describedtherein can be applied in the present invention. In the case ofemploying a plastic substrate having low heat resistance, a transparentanode film-formed using ITO or IZO at a low temperature of 150° C. orless is preferred.

<Cathode>

The cathode is usually sufficient if it has a function as an electrodeof injecting an electron in the organic compound layer. The shape,structure, size and the like thereof are not particularly limited, andthe cathode material may be appropriately selected from known electrodematerials according to the usage or purpose of the light-emittingdevice.

Examples of the material constituting the cathode include a metal, analloy, a metal oxide, an electrically conducting compound and a mixturethereof. Specific examples thereof include an alkali metal (e.g., Li,Na, K, Cs), an alkaline earth metal (e.g., Mg, Ca), gold, silver, lead,aluminum, a sodium-potassium alloy, a lithium-aluminum alloy, amagnesium-silver alloy, and a rare earth metal such as indium andytterbium. One species of these materials may be used alone, but in viewof satisfying both stability and electron-injecting property, two ormore species may be suitably used in combination.

Among these materials constituting the cathode, an alkali metal and analkaline earth metal are preferred in view of electron-injectingproperty, and a material mainly comprising aluminum is preferred in viewof excellent storage stability.

The “material mainly comprising aluminum” indicates aluminum alone or analloy or mixture of aluminum with 0.01 to 10 mass % of an alkali metalor alkaline earth metal (for example, a lithium-aluminum alloy and amagnesium-aluminum alloy).

Incidentally, the cathode material is described in detail inJP-A-2-15595 and JP-A-5-121172, and the materials described therein canbe applied also in the present invention.

The method for forming the cathode is not particularly limited, and thecathode may be formed according to known methods. For example, thecathode may be formed by a method appropriately selected, inconsideration of suitability for the material constituting the cathode,from a wet system such as printing and coating, a physical system suchas vacuum deposition, sputtering and ion plating, and a chemical systemsuch as CVD and plasma CVD. For example, in the case of selecting ametal or the like as the cathode material, one species or two or morespecies thereof may be sputtered simultaneously or sequentially.

The patterning when forming the cathode may be performed by chemicaletching such as photolithography, by physical etching using a laser orthe like, by vacuum deposition or sputtering using a mask, or by alift-off method or printing method.

In the present invention, the position where the cathode is formed isnot particularly limited, and the cathode may be formed entirely orpartially on the organic compound layer.

A dielectric layer comprising a fluoride, oxide or the like of an alkalimetal or alkaline earth metal may be inserted between the cathode andthe organic compound layer to have a thickness of 0.1 to 5 nm. Thisdielectric layer may be regarded as a kind of electron injection layer.The dielectric layer can be formed, for example, by a vacuum vapordeposition method, a sputtering method or an ion plating method.

The thickness of the cathode may be appropriately selected according tothe material constituting the cathode and cannot be indiscriminatelyspecified but is usually on the order of 10 nm to 5 μm, preferably from50 nm to 1 μm.

The cathode may be transparent or opaque. The transparent cathode may beformed by film-forming the cathode material to a small thickness of 1 to10 nm and further stacking thereon a transparent electrically conductingmaterial such as ITO and IZO.

<Organic Compound Layer>

The organic compound layer for use in the present invention is describedbelow.

The organic electroluminescent device of the present invention has atleast one organic compound layer including a light-emitting layer, andthe organic compound layer other than the light-emitting layer includes,as described above, layers such as hole transport layer, electrontransport layer, charge blocking layer, hole injection layer andelectron injection layer.

—Formation of Organic Compound Layer—

In the organic electroluminescent device of the present invention, thelayers constituting the organic compound layer each may be suitablyformed by any method such as dry film-forming method (e.g., vapordeposition, sputtering), transfer method and printing method.

—Organic Light-Emitting Layer—

The organic light-emitting layer is a layer having a function of, whenan electric field is applied, receiving a hole from the anode, holeinjection layer or hole transport layer, receiving an electron from thecathode, electron injection layer or electron transport layer, andproviding a site for recombination of a hole and an electron, therebyemitting light.

In the present invention, the light-emitting layer may be composed ofonly a light-emitting material or may have a mixed layer structure of ahost material and a light-emitting material. The light-emitting materialmay be either a fluorescent material or a phosphorescent material and asfor the dopant, one species or two or more species may be used. The hostmaterial is preferably a charge transport material. As for the hostmaterial, one species or two or more species may be used, and examplesthereof include a construction where an electron-transporting hostmaterial and a hole-transporting host material are mixed. Also, thelight-emitting layer may contain a material which does not have electrontransport property and does not emit light.

Furthermore, the light-emitting layer may be composed of one layer ortwo or more layers, and the layers may differ in the color of lightemitted.

Examples of the fluorescent material which can be used in the presentinvention include a benzoxazole derivative, a benzimidazole derivative,a benzothiazole derivative, a styrylbenzene derivative, a polyphenylderivative, a diphenylbutadiene derivative, a tetraphenyl-butadienederivative, a naphthalimide derivative, a coumarin derivative, acondensed aromatic compound, a perynone derivative, an oxadiazolederivative, an oxazine derivative, an aldazine derivative, a pyralidinederivative, a cyclopentadiene derivative, a bis-styrylanthracenederivative, a quinacridone derivative, a pyrrolopyridine derivative, athiadiazolopyridine derivative, a cyclopentadiene derivative, astyrylamine derivative, a diketopyrrolopyrrole derivative, an aromaticdimethylidine compound, various metal complexes as represented by ametal complex of 8-quinolinol derivative and a metal complex ofpyrromethene derivative, a polymer compound such as polythiophene,polyphenylene and polyphenylenevinylene, and a compound such as organicsilane derivative.

Examples of the phosphorescent material which can be used in the presentinvention include a complex containing a transition metal atom or alanthanoid atom.

The transition metal atom is not particularly limited, but preferredexamples thereof include ruthenium, rhodium, palladium, tungsten,rhenium, osmium, iridium and platinum, with rhenium, iridium andplatinum being more preferred.

Examples of the lanthanoid atom include lanthanum, cerium, praseodymium,neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium,erbium, thulium, ytterbium and lutetium. Among these lanthanoid atoms,neodymium, europium and gadolinium are preferred.

Examples of the ligand of the complex include the ligands described inG. Wilkinson et al., Comprehensive Coordination Chemistry, PergamonPress (1987), H. Yersin, Photochemistry and Photophysics of CoordinationCompounds, Springer-Verlag (1987), and Akio Yamamoto, Yuki KinzokuKagaku-Kiso to Oyo-(Metalorganic Chemistry—Foundation and Application—),Shokabo (1982).

Specifically, the ligand is preferably a halogen ligand (preferablychlorine ligand), a nitrogen-containing heterocyclic ligand (e.g.,phenylpyridine, benzoquinoline, quinolinol, bipyridyl, phenanthroline),a diketone ligand (e.g., acetylacetone), a carboxylic acid ligand (e.g.,acetic acid ligand), a carbon monoxide ligand, an isonitrile ligand or acyano ligand, more preferably a nitrogen-containing heterocyclic ligandis more preferred. The complex may have one transition metal atom in thecompound or may be a so-called dinuclear complex having two or moretransition metal atoms. Different kinds of metal atoms may be containedat the same time.

The phosphorescent material is preferably an iridium complex or aplatinum complex, more preferably a tetradentate platinum complex or aniridium complex having a fluorine-substituted phenylpyridine as aligand.

The phosphorescent material is preferably contained in thelight-emitting layer in an amount of 0.1 to 40 mass %, more preferablyfrom 0.5 to 20 mass %.

Examples of the host material contained in the light-emitting layer ofthe present invention include, other than the compound of the presentinvention, the materials having a carbazole skeleton, a diarylamineskeleton, a pyridine skeleton, a pyrazine skeleton, a triazine skeletonor an arylsilane skeleton, and the materials described later in theparagraphs of hole injection layer, hole transport layer, electroninjection layer and electron transport layer.

The thickness of the light-emitting layer is not particularly limitedbut usually, the thickness is preferably from 1 to 500 nm, morepreferably from 5 to 200 nm, still more preferably from 10 to 100 nm.

—Hole Injection Layer, Hole Transport Layer—

The hole injection layer and hole transport layer are a layer having afunction of receiving a hole from the anode or anode side andtransporting it to the cathode side. Specifically, the hole injectionlayer and hole transport layer each is preferably a layer containing,other than the compound of the present invention, a carbazolederivative, a triazole derivative, an oxazole derivative, an oxadiazolederivative, an imidazole derivative, a polyarylalkane derivative, apyrazoline derivative, a pyrazolone derivative, a phenylenediaminederivative, an arylamine derivative, an amino-substituted chalconederivative, a styrylanthracene derivative, a fluorenone derivative, ahydrazone derivative, a stilbene derivative, a silazane derivative, anaromatic tertiary amine compound, a styrylamine compound, an aromaticdimethylidyne-based compound, a porphyrin-based compound, an organicsilane compound, carbon or the like.

The thickness of each of the hole injection layer and the hole transportlayer is preferably 500 nm or less from the standpoint of lowering thedriving voltage.

The thickness of the hole transport layer is preferably from 1 to 500nm, more preferably from 5 to 200 nm, still more preferably from 10 to100 nm, and the thickness of the hole injection layer is preferably from0.1 to 200 nm, more preferably from 0.5 to 100 nm, still more preferablyfrom 1 to 100 nm.

The hole injection layer and hole transport layer each may have asingle-layer structure comprising one species or two or more species ofthe above-described materials or may have a multilayer structurecomprising a plurality of layers having the same composition ordifferent compositions.

—Electron Injection Layer, Electron Transport Layer—

The electron injection layer and electron transport layer are a layerhaving a function of receiving an electron from the cathode or cathodeside and transporting it to the anode side. Specifically, the electroninjection layer and electron transport layer each is preferably a layercontaining, other than the compound of the present invention, a triazolederivative, an oxazole derivative, an oxadiazole derivative, animidazole derivative, a fluorenone derivative, an anthraquinodimethanederivative, an anthrone derivative, a diphenylquinone derivative, athiopyran dioxide derivative, a carbodiimide derivative, afluorenylidenemethane derivative, a distyrylpyrazine derivative, anaromatic ring tetracarboxylic acid anhydride such as naphthalene andperylene, a phthalocyanine derivative, various metal complexes asrepresented by a metal complex of 8-quinolinol derivative and a metalcomplex having metal phthalocyanine, benzoxazole or benzothiazole as aligand, an organic silane derivative or the like.

The thickness of each of the electron injection layer and the electrontransport layer is preferably 500 nm or less from the standpoint oflowering the driving voltage.

The thickness of the electron transport layer is preferably from 1 to500 nm, more preferably from 5 to 200 nm, still more preferably from 10to 100 nm, and the thickness of the electron injection layer ispreferably from 0.1 to 200 nm, more preferably from 0.2 to 100 nm, stillmore preferably from 0.5 to 50 nm.

The electron injection layer and electron transport layer each may havea single-layer structure comprising one species or two or more speciesof the above-described materials or may have a multilayer structurecomprising a plurality of layers having the same composition ordifferent compositions.

—Hole Blocking Layer—

The hole blocking layer is a layer having a function of preventing thehole transported from the anode side to the light-emitting layer, frompenetrating to the cathode side.

Examples of the organic compound constituting the hole blocking layerinclude, other than the compound of the present invention, an aluminumcomplex such as BAlq, a triazole derivative, and a phenanthrolinederivative such as BCP.

The thickness of the hole blocking layer is preferably from 1 to 500 nm,more preferably from 5 to 200 nm, still more preferably from 10 to 100nm.

The hole blocking layer may have a single-layer structure comprising onespecies or two or more species of the above-described materials or mayhave a multilayer structure comprising a plurality of layers having thesame composition or different compositions.

<Protective Layer>

In the present invention, the entire organic EL device may be protectedby a protective layer.

The material contained in the protective layer may be sufficient if ithas a function of preventing a device deterioration promoter such asmoisture and oxygen from intruding into the device.

Specific examples thereof include a metal such as In, Sn, Pb, Au, Cu,Ag, Al, Ti and Ni, a metal oxide such as MgO, SiO, SiO₂, Al₂O₃, GeO,NiO, CaO, BaO, Fe₂O₃, Y₂O₃ and TiO₂, a metal nitride such as SiN_(x) andSiN_(x)O_(y), a metal fluoride such as MgF₂, LiF, AlF₃ and CaF₂,polyethylene, polypropylene, polymethyl methacrylate, polyimide,polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene,polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene anddichlorodifluoroethylene, a copolymer obtained by copolymerizing amonomer mixture containing tetrafluoroethylene and at least onecomonomer, a fluorine-containing copolymer having a cyclic structure inthe copolymer main chain, a water-absorbing substance having a waterabsorption percentage of 1% or more, and a moisture-proof substancehaving a water absorption percentage of 0.1% or less.

The method for forming the protective layer is not particularly limited,and examples of the method which can be applied include a vacuumdeposition method, a sputtering method, a reactive sputtering method, anMBE method, a cluster ion beam method, an ion plating method, a plasmapolymerization method (high-frequency excitation ion plating method), aplasma CVD method, a laser CVD method, a thermal CVD method, a gassource CVD method, a coating method, a printing method and a transfermethod.

<Encapsulation>

The organic electroluminescent device of the present invention may besubjected to encapsulation of the entire device by using a sealingcontainer.

Also, a moisture absorbent or an inactive liquid may be enclosed in thespace between the sealing container and the light-emitting device. Themoisture absorbent is not particularly limited but examples thereofinclude barium oxide, sodium oxide, potassium oxide, calcium oxide,sodium sulfate, calcium sulfate, magnesium sulfate, phosphoruspentoxide, calcium chloride, magnesium chloride, copper chloride, cesiumfluoride, niobium fluoride, calcium bromide, vanadium bromide, molecularsieve, zeolite and magnesium oxide. The inactive liquid is notparticularly limited but examples thereof include paraffins, liquidparaffins, a fluorine-based solvent such as perfluoroalkane,perfluoroamine and perfluoroether, a chlorine-based solvent and siliconeoils.

In the organic electroluminescent device of the present invention, a DC(if desired, may contain an AC component) voltage (usually from 2 to 15V) or a DC current is applied between the anode and the cathode, wherebylight emission can be obtained.

As for the driving method of the organic electro-luminescent device ofthe present invention, the driving methods described, for example, inJP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558,JP-A-8-234685, JP-A-8-241047, Japanese Patent 2,784,615, and U.S. Pat.Nos. 5,828,429 and 6,023,308 may be applied.

EXAMPLES Comparative Example 1

A 0.5 mm-thick and 2.5 cm-square glass substrate with an ITO film(produced by GEOMATEC Company Limited, surface resistance: 10 Ω/square)was placed in a cleaning vessel and after ultrasonic cleaning in2-propanol, treated with UV-ozone for 30 minutes. On this transparentanode (ITO film), the following organic compound layers weresequentially vapor-deposited by a vacuum deposition method.

Unless otherwise indicated, the vapor deposition speed in Examples ofthe present invention is 0.2 nm/sec. The vapor deposition speed wasmeasured by using a crystal oscillator. In the following, the filmthickness is also a value measured by using a crystal oscillator.

(First Hole Transport Layer)

Copper phthalocyanine: film thickness of 10 nm.

(Second Hole Transport Layer)

NPD: film thickness of 40 nm.

(Light-Emitting Layer)

[CBP (90 mass %)+Firpic] layer: film thickness of 30 nm.

(First Electron Transport Layer)

BAlq: film thickness of 10 nm.

(Second Electron Transport Layer)

Alq: film thickness of 10 nm.

Finally, lithium fluoride of 0.1 nm and metallic aluminum of 100 nm werevapor-deposited in this order to form a cathode.

The resulting structure was placed in a glove box replaced with an argongas, while keeping it away from contact with air, and encapsulated byusing a stainless steel-made sealing can and an ultraviolet-curableadhesive (XNR5516HV, produced by Nagase-Ciba) to obtain an organicelectroluminescent device of Comparative Example 1.

Comparative Example 2

An organic electroluminescent device of Comparative Example 2 wasproduced in the same manner as the organic electroluminescent device of<Comparative Example 1> except for changing CBP to Compound (XVI) (acompound described in JP-A-2002-356449).

Chemical structures of copper phthalocyanine, NPD, CBP, Firpic, Alq,BAlq and Compound (XVI) are shown below.

Example 1

An organic electroluminescent device of Example 1 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing CBP to Compound 10 of the presentinvention.

Example 2

An organic electroluminescent device of Example 2 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing CBP to Compound 48 of the presentinvention.

Example 3

An organic electroluminescent device of Example 3 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing CBP to Compound 89 of the presentinvention.

Example 4

An organic electroluminescent device of Example 4 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing CBP to Compound 165 of the presentinvention.

Example 5

An organic electroluminescent device of Example 5 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing CBP to Compound 62 of the presentinvention.

Example 6

An organic electroluminescent device of Example 6 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing CBP to Compound 114 of the presentinvention.

Example 7

An organic electroluminescent device of Example 7 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing CBP to Compound 153 of the presentinvention.

A voltage of 10 V was applied to each of the devices of Examples 1 to 7and Comparative Examples 1 and 2, as a result, light emission originatedfrom Firpic was obtained in the light-emitting devices of Examples 1 to7 and Comparative Example 1, but light emission originated from Firpicwas not observed in the device of Comparative Example 2.

The relative ratio of brightness when the devices of Examples 1 to 7 andComparative Example 1 were driven by an applied voltage of 10 V, and thebrightness half-life of the devices of Examples 1 to 7 and ComparativeExample 1 are shown in Table 1. The brightness half-life was measured asthe time t_(0.5) in which the brightness is decreased to 50% of theinitial brightness, by setting the device in OLED Test System Model ST-Dmanufactured by Tokyo Systems Development Co., Ltd. and driving it in aconstant current mode under the condition of a forward constant currentof 0.4 mA.

TABLE 1 Relative Value of Brightness Brightness Half-Life Comparative 16 minutes Example 1 Example 1 5 9 hours Example 2 12 10 hours Example 39 6 hours Example 4 11 7 hours Example 5 10 7 hours Example 6 5 4 hoursExample 7 5 3 hours

Example 8

An organic electroluminescent device of Example 8 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing BAlq to Compound 160 of the presentinvention.

The relative ratio of brightness when the devices of Example 8 andComparative Example 1 were driven by an applied voltage of 10 V was 4:1.

Example 9

An organic electroluminescent device of Example 9 was produced in thesame manner as the organic electro-luminescent device of <ComparativeExample 1> except for changing NPD to Compound 34 of the presentinvention.

The relative ratio of brightness when the devices of Example 9 andComparative Example 1 were driven by an applied voltage of 10 V was 5:1.

As verified in Examples above, an organic electro-luminescent devicewith high efficiency and high durability can be obtained by using thecompound of the present invention.

The organic electroluminescent device of the present invention ischaracterized by comprising at least one species of the compoundsrepresented by formula (1) to (5) of the present invention (in thespecification, used in the same meaning as the “compound of the presentinvention”). By virtue of this construction, an organicelectro-luminescent device (in the present specification, used in thesame meaning as the “device of the present invention”) assured of highemission efficiency (for example, external quantum efficiency) andexcellent durability can be provided. Also, by virtue of using thecompound of the present invention having a specific structure, a devicecapable of emitting light with high emission efficiency in the blueregion and assured of excellent durability can be provided.

The entire disclosure of each and every foreign patent application fromwhich the benefit of foreign priority has been claimed in the presentapplication is incorporated herein by reference, as if fully set forth.

What is claimed is:
 1. An organic electroluminescent device, whichcomprises: a pair of electrodes; and at least one organic compound layerbetween the pair of electrodes, the at least one organic compound layercomprising at least a light-emitting layer, wherein at least one of theat least one organic compound layer comprises at least one compoundrepresented by formula (2):

wherein A1 and A2 each independently represents a carbon atom or anitrogen atom; Q⁵ and Q⁶ each independently represents an atomic groupfor forming an aromatic hydrocarbon ring or an aromatic heterocyclicring in combination with A¹ and A² respectively, provided that Q⁵ and Q⁶are not combined through a single bond, a divalent aromatic hydrocarbonring group or a divalent aromatic heterocyclic ring group; A²⁰¹ to A²¹⁶each independently represents N or C—R²⁰¹ to C—R²¹⁶; and R²⁰¹ to R²¹⁶each independently represents a hydrogen atom or a substituent.